The present invention relates to a power tool having a reciprocating, and sometimes oscillating, saw blade holder. More particularly, the invention relates to a self-lubrication system forming part of the drive mechanism which imparts reciprocating movement to the saw blade holder.
Reciprocating power saws of the type under consideration are normally electrically powered and employ a mechanical drive system to convert rotary movement of the motor shaft to reciprocating movement of the saw blade holder. Needless to say, it is necessary that these fast-moving mechanical parts be properly lubricated. (For prior art of general interest, attention is invited to U.S. Pat. Nos. 2,139,189, 2,258,138 and 3,461,732.)
Power tools of the type under discussion are portable and consequently must be of light-weight and compact construction to the extent possible. Thus, space and weight requirements dictate that a separate pump cannot be employed to provide the moving parts with a suitable lubricant. (See U.S. Pat. Nos. 2,184,461 and 3,938,622 for a showing of a separate lubrication pump in a chain saw.) Further, the immersion of all of the moving parts in a body of oil or grease is not feasible as expensive seals, particularly in the area of the reciprocating tool holder, would be needed to prevent leakage of the lubricant to the exterior of the tool housing. Accordingly, there is a long-felt need in the art for an efficient, light-weight and compact lubrication system for the drive mechanism of a reciprocating power tool.